A lateral airbag basically consists of a folded bag which is quickly inflated by means of a gas produced by a generator when certain sensor devices detect a vehicle collision. The bag is thus deployed between the vehicle occupant and, usually, a vehicle door and protects him or her during the collision.
In the normal bag deployment operation, the internal pressure produced by the generator upon filling it with gas can be sufficiently high to cause the bag to be so hard that the occupant rebounds. To prevent this drawback, such bags have been provided with a vent hole which is used to reduce the internal pressure of the bag and therefore the possibility of causing injuries when they are activated.
In turn, the use of several means for plugging this vent hole is known so as to achieve a better control of internal pressure in the bag than that provided exclusively by the variation of the dimension of the hole. In this sense, the use of patches to prevent the gas from immediately leaving through the discharge hole, but rather to leave when the patch breaks upon reaching a certain pressure inside the bag, must be emphasized. The art has proposed different types of patches with different means for controlling its breakage according, to a greater or lesser extent, to a certain resistance to the gas pressure inside the bag. The presence of the necessary gas pressure for the bag to fulfill its protective function is thus made compatible with the assurance that the gas pressure will not a reach an excessive value, with the risk for the persons on which the bag is deployed.
In addition, the need has also arisen for vent devices which allow increasing the gas outflow according to the specific characteristics of each collision and of the type of passenger affected and in this sense, several solutions of vent devices are also known offering vent holes with an adjustable surface, facilitating the increase of the vent area as the internal pressure in the bag increases.
A new need which has arisen considers the need for airbags which allow reducing the vent area, even eliminating it completely, in certain impact conditions, which requires blocking mechanisms which must operate in an opposite manner to those indicated. The aforementioned traditional patches had to completely plug the outlet until the internal pressure of the gas in the bag did not reach a certain level and later they broke and stopped acting, now the opposite is required: devices which allow blocking the vent hole in certain situations.
Some proposals are know to that effect such as that described in document WO 2006/050757, relating to a multichamber bag which can provide different hardness levels depending on the size of the occupant. Said bag contains at least one auxiliary chamber the function of which is to regulate the pressure in the main chamber or chambers. Gas is discharged through a vent hole located in the auxiliary chamber, which vent hole incorporates a device which allows blocking the exit of gas in the event that the occupant is tall. This proposal provides a side airbag with an adaptive capacity for the size of the occupant but its drawback is that it lacks adaptive capacity for different crash configurations.
In addition, another type of proposals of adaptive side airbags is known, such as that described in patent document U.S. Pat. No. 6,976,702 relating to a two-chamber (pelvis-chest) bag with the generator located in the lower chamber (pelvis chamber) and in which the upper chamber (chest chamber) is inflated from the lower chamber so as to achieve moving the occupant due to the high pressure obtained in the lower chamber which does not have a vent area. As in the previous case, the drawback of this proposal is that it lacks adaptive capacity for different crash configurations.
The present invention is aimed at solving said drawbacks.